A common drawback of known light guides used for light devices of motor vehicles is the fact that a certain part of the light conducted by the light guide escapes from the light guide another way than via the output surface of the light guide without this part of the light being further used, which reduces the light efficiency of the light guide. Therefore, in the field of the design of light guides and light guiding systems, there is a permanent effort to propose such designs that will bring an increase of their light efficiency.
An example of a known design of a light guide that strives to increase light efficiency is the solution described in the patent U.S. Pat. No. 7,726,854. This solution entails using a surface fitted with a diffusion material that is arranged in parallel to the light guide against its reflective surface at a certain distance from the light guide. Light rays that escape out of the light guide through its reflective surface fall onto the diffusion surface and are returned back to the light guide via the reflective surface. Given the diffusion properties of the surface from which the rays are returned to the light guide, homogeneous distribution of the light rays returned to the light guide is achieved all along the length of the light guide. This solution is based on the diffusion properties of the surface from which the light rays return to the light guide.